This invention relates to remotely actuated devices used to couple two units, which devices will upon command part the coupling link allowing the two units to part. More specifically, this invention is directed to a device where the release is effected by the remotely actuated melting of a segment of the connective link.
One application requiring the use of such devices is the tethering of a bouyant body in a fluid. Underwater instrumentation activities frequently require that a buoyant instrumentation package be tethered to the floor of a body of water. After the desired period of data gathering, the package is released from the tether so that it may float to the surface and be recovered. Such release devices are typically actuated by a remote acoustical signal from the recovery ship. Upon receipt of the proper coded acoustical signal, a battery powered release mechanism is actuated. Other applications requiring the separation of two coupled units upon remote command can be envisioned.
In underwater applications, the release mechanism used is frequently an explosive link. Such links do not exhibit the desired degree of reliability and have the added disadvantage of not working in the high pressure environment of deep waters. A second type of release device is the so-called electrolysis link. On this device the release link is insulated from the sea water except for a small area. The link is generally made of titanium or stainless steel. Upon receiving the remote actuation signal a current is passed through the water with this exposed area of the link as the anode. Stray current corrosion quickly corrodes the link (1-20 minutes depending up type, size). This release mechanism has the drawback that its performance is degraded by biofouling. Currently the preferred release mechanism is a mechanical release. Release devices employing a mechanical release typically use a battery powered motor to unscrew a pin, rotate a hook, or perform other similar decoupling actions. The complexity of such devices in combination with the limited market makes the mechanical release devices higher priced than the explosive or corrosible release devices.
One embodiment of the present invention provides an inexpensive reliable remotely actuated release device for tethering equipment packages to the bottom of bodies of water. The device is operable in water depths in excess of 20,000 feet and its reliability is not affected by high salinity of the water. These requirements could only be met by the most expensive of the existing prior art devices. In addition, the present invention offers the same advantages of low cost and reliability when used in other decoupling applications.